Obstetric care of one of the most common and costly elements of medical practice, yet there is relatively little information about what comprises the content and variation in obstetric care in the United States. Over 3,000,000 deliveries occur in the United States annually, with be total expense approaching $20 billion annually. The average cost for an uncomplicated pregnancy course is over $4,300 representing one-fifth of a typical couple's annual budget. As a result of rapidly rising obstetric costs, an increasing percentage of women are unable to pay for obstetric care. As a result, state and federal support of obstetric care has increased rapidly, with Medicaid paying for 630,000 deliveries-17 percent of all birth. The purpose of this proposal is to determine the content and range of variation in prevailing medical protocols for low-risk pregnancies and to determine the factors the explain perceived variations. A stratified random sample of all obstetric providers in the state of Washington will be selected from a roster of all licensed providers. The patient universe be defined as allow-risk woman who begin prenatal care in the first trimester of pregnancy. A random sample of all these patients will be selected and charts abstracted detailing cAre received both during the prenatal and intrapartum period. The usual prenatal and obstetric protocol will be determined for each of the sample physicians. Charges associated with these protocols will be determined as a proxy for cost and will be used as a dependent variable in this study. Independent variables collected will include the training and experience of physician or midwife attending the birth, the characteristics of the birth setting, the malpractice experience of the provider, and the characteristics of the patients. This study will allow a precise definition of the prevailing ways in which pregnancy is treated, determine the extent to which variation in clinical protocols is associated with differences in costs, and permit the identification of these patient, provider, or environmental factors that are associated with these medical care variations. To the extent that practice variations in prenatal and intrapartum care lead to increased consumption of medical resources without commensurate improvements in patient outcomes, it may be possible to reduce the cost of routine obstetrical care for this population without impairing patient outcomes.